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AimsEdit

  • Statistical free radical copolymerization
  • Copolymer composition


IntroductionEdit

  • Polymerization of two or more monomers
  • Properties of the polymer depend on monomer composition and time


Statistical copolymerizationEdit

RM1• + M1 → RM1M1 rate=k11[RM1•][M1]
RM1• + M2 → RM1M2 rate=k12[RM1•][M2]
RM2• + M1 → RM2M1 rate=k21[RM2•][M1]
RM2• + M2 → RM2M2 rate=k22[RM2•][M2]
  • Monomers are consumed at different rates
  • Therefore the polymer composition changes during the reaction


Instantaneous copolymer equation

 


  • Defines the polymer composition at any moment in time.
  • FA = amount of monomer A in the polymer.
  • fA = amount of monomer A in the monomer feed.
  • FA + FB = 1
  • fA + fB = 1


Reactivity ratios

  and  


  • Defines the relative rates of reaction.
  • Ratios are set for any pair of monomers.
  • No variation with solvent, concentration, temperature, etc.


rA > 1 → HOMO propagation preferred

rA < 1 → CROSS propagation preferred